Method for producing aerosol/resonance cavities (bubbles)

ABSTRACT

The present invention relates to methods for producing an aerosol and may be useful in chemical, petrochemical and pharmaceutical industries, as well as in household applications, in medicine. The method for producing an aerosol consists in subjecting the medium to be dispersed to the action of ultrasonic oscillations with the help of a source of oscillations, containing a piezoelectric element. The source of oscillations is made with a possibility of dispersing a liquid and/or loose medium and adjusting the size of aerosol drops by varying the oscillations, the liquid and/or loose medium to be dispersed being acted upon in a standing-wave mode. The frequency of oscillations is varied within a range close to the resonance frequency of the macrostructure of the liquid and/or loose medium to be dispersed, and/or is maintained equal to the resonance frequency of the macrostructure of the liquid and/or loose medium to be dispersed. A fine-dispersed aerosol is formed, with a size of drops not larger than 0.5 μm, followed by regeneration of the dispersed medium macrostructure, i.e., of the geometry of the total active surface (which, essentially, intensifies the selected physicochemical process)

The present invention relates to methods for producing an aerosol (aswell as a gel or cavitation bubbles) and to controlling physicochemicalprocesses in a heterophase medium (or media). The invention may beuseful in chemical, petrochemical and pharmaceutical industries, as wellas in household applications, in medicine, and also in units forpreparing fuel mixtures in internal combustion engines (for instance, ina diesel engine nozzle).

It is known that in heterophase systems, e.g., such as a gaseousreaction medium—catalyst surface, in the course of reaction (phasetransition) there takes place an effect of origination of surfacemacrostructures (from islets of reagents, intermediate products). Thegeometrical type of such structures strictly corresponds to the reactiondynamics (see [1]-[4]). For instance, in [11] experimental results onSAWRS-control over the process of growth of semiconductor films inCVD-chambers are discussed. The existence of autocatalytic growtheffects and the origination of surface submillimeter macrostructurescontrolling the reaction rates are shown. It should be noted that forthe reactions on the “gas-solid” interface characteristic resonancefrequencies lie within 0.8-10 MHz (in the general case, thecharacteristic dimensions of the microstructures are 0.1-15 mm). Thislimits substantially the linear dimensions of the catalyst (support)excited by ultrasound for induced creation of the requiredmacrostructures. For industrial (large-scale) application it istherefore expedient to use aerosols or gels (prepared “separately”) suchthat their particles per se are the required macrostructures, i.e., havenatural frequencies that are characteristic of the selected reactions.It should be noted that submicron drops of viscous liquids (forinstance, of oils) have low-frequency megahertz natural modes ofoscillations owing to “self-consistent” volume-surface excitations.

Closest to the present invention is the known method of producing anaerosol, consisting in that the dispersed medium is subjected to theaction of ultrasonic oscillations by means of a source of oscillationscomprising a piezoelectric element. [5].

The known method is disadvantageous in a low effectiveness of thecatalytic activity of the formed macrostructures, i.e., in a loweffectiveness of dispersing the medium, conditioned by low selectivityof the process of formation of macrostructures (of aerosol, gel orcavitation bubbles). When liquid catalysts are used, degradation of themacrostructures in the course of the physicochemical process is aparticularly topical factor responsible for lowering the effectivenessof the proposed method.

The essence of the invention is, in particular, to enhance theefficiency of dispersing owing to intensive regeneration ofmacrostructures, providing resonance growth of the rate ofphysicochemical process.

The posed problem is solved by that the medium to be dispersed, which isusually multicomponent, is subjected to the action of ultrasonicoscillations with the help of a source of oscillations comprising apiezoelectric element. The source of oscillations, which is made with apossibility of dispersing a liquid and/or loose medium and adjusting thesize of aerosol drops by varying the oscillation s, the liquid and/orloose medium to be dispersed is acted upon in a standing-wave mode. Thefrequency of oscillations is varied within a range close to theresonance frequency of the macrostructure of the liquid and/or loosemedium to be dispersed, and/or is maintained equal to the resonancefrequency of the macrostructure of the liquid and/or loose medium to bedispersed, i.e., the resonance frequency lies within the band(s) of theresonant growth of the rate of the process of for—mation (escape) ofaerosol drops (gel drops or cavitation bubbles). During the process,oscillations are maintained in the system, which ensure regeneration ofthe relief of the selected macrostructure—of an ensemble of the obtainedmedium interfaces, which produces an effect of catalytic acceleration ofthe process. Upon formation (escape) of aerosol drops a fine-dispersedaerosol is formed with the size of drops not exceeding 0.5 μm, followedby the regeneration of the macrostructure of the dispersed medium, i.e.,of the geometry of the total active surface (which, essentially,intensifies the selected physicochemical process).

The invention is explained by the accompanying drawings.

FIG. 1 shows a device for carrying out the claimed method.

The method for producing an aerosol consists in that a medium to bedispersed is subjected to the effect of ultrasonic oscillations with thehelp of a source of oscillations, comprising a piezoelectric elementwhich is made with a possibility of dispersing a liquid and/or loosemedium and adjusting the size of aerosol drops by varying theoscillations, the liquid and/or loose medium to be dispersed is actedupon in a standing-wave mode. The frequency of oscillations is variedwithin a range close to the resonance frequency of the macrostructure ofthe liquid and/or loose medium to be dispersed, and/or is maintainedequal to the resonance frequency of the macrostructure of the liquidand/or loose medium to be dispersed. A fine-dispersed aerosol is formedwith the size of drops not exceeding 0.5 μm, followed by theregeneration of the macrostructure of the dispersed medium, i.e., of thegeometry of the total active surface (which, essentially, intensifiesthe selected physicochemical process). It should be noted that incarrying out said method, in particular, when producing ultradispersedliquid aerosols, the surface of the liquid medium acts as the processcatalyst. Microdrops of a suitable size per se are macrostructureshaving a characteristic acoustic resonance frequency, i.e., in thepresent case, the catalyst relief is an ensemble of the aerosol dropsurfaces, and therefore, having measured the characteristic resonancefrequency of the medium (or media) being dispersed (for example, asdisclosed in [10]), we can provide the creation (and regeneration) of arelief of macrostructures accelerating the selected physicochemicalprocess (of dispersing), by generating ultradispersed drops. Naturally,it is expedient to maintain the relief of the selected macrostructure inthe system by exciting a standing wave pattern at the given frequencies[10] by creating the relief mechanically: by selecting the injectorchannel geometry, by creating regular lattices in the areas of flowvelocity steps, etc. The simplicity of generating aerosols of liquidmedia (liquids), as well as gels or bubbles, makes it possible to useeffectively resonance effects when working with liquid catalysts ontremendous active surfaces (as compared with the wavelengths).

The device for carrying out the claimed method comprises an amplifierelement 1 of a generator, a piezoelectric element 2 of the evaporationsystem embraced by a positive feedback loop 3, serving as a baseoscillatory circuit which presets the generator oscillation frequency, amedium 4 to be dispersed, which is in acoustic contact with thepiezoelectric element.

An aerosol is produced in the following manner. When the generatorconsisting of the elements 1 and 2 embraced by a positive feedback loop3 is enabled, electric oscillations are generated. These electricoscillations are converted in the piezoelectric element 2 into astanding acoustic wave which acts on the medium (e.g., liquid) 4. Underthe effect of acoustic action of the piezoelectric element 2, a processof dispersing the liquid 4 starts therein, which is accompanied by theorigination of surface macrostructures to which there correspondcharacteristic acoustic resonance frequencies. The processes associatedwith the macrostructures originating in dispersing the (desired) liquidcomponent vary the acoustic characteristics of the surface of thepiezoelectric element at the characteristic resonance frequencies. Thegenerator is controlled by the positive feedback loop 3 which amplifiesthe signals characterizing the action of the desirable processes in theliquid 4 being dispersed on the overall performance of the connectedoscillatory circuits.

For example, a device realized on said principles can be used fordispersing essential oils of medicinal plants. Ultradispersed aerosolsof oils thus produces are noted for a high sanifying (bactericidal)effect, this being associated with the resonant growth of the chemicalactivity of the surface of microdrops. This makes it possible to“catalyze” the biological interaction of the aerosol and bacteria,whereby the sanifying effect is substantially enhanced. The claimedmethod enables an essential broadening, in particular, of the field ofmedicinal application of essential oils of medicinal plants. The deviceoperation at megahertz frequencies with densities of the ultrasonicactive power on the order of 1 W/cm² makes it possible to produceaerosols with the diameter of drops smaller than 0.5 μm, whereby a higheffectiveness of the sanifying action of the instrument is ensured. Theapplication of fine dispersed aerosols produced both from purifiedessential oils and directly from live tissues of medicinal plants by themethod of resonance high-frequency ultrasonic sublimation substantiallybroadens the range of therapeutic effects of the producers of medicinalplants, the properties of the produced resonance aerosols differing fromthe properties of aerosols produced with the aid of conventional devices(including ultrasonic ones).

REFERENCES

-   [1] V. A. Agranat (Ed.), “Ultrasonic Technology”, Moscow,    Metallurgiya, pp. 341-368 (in Russian).-   [2] Chemical Physics Letters. Volume 191, number 5, 1992:    “Observation of surface acoustic phonon resonances: application to    the CO+O₂ oscillatory reaction on Pt{100}”. V. N. Brezhnev, A. I.    Boronin, V. P. Ostanin, V. S. Tupikov and A. N. Belyaev.-   [3] 13th European Conference on Surface Science Warwick (UK), August    199:3, “The phonon mechanism of self-organization in catalysis. The    example of oscillatory reaction CO+O₂ on Pt{100}.” V. N.    Brezhnev, A. I. Boronin, V. P. Ostanin.-   [4] Physics of low-dimensional structures. 2/3 (1995), pp. 119-126.    “Capabilities of the SAWRS Method in Ultra-High Vacuum    Studies” N. V. Brezhnev, A. V. Pryanichnikov, S. P. Suprun, V. S.    Tupikov).-   [5] Patent RU No. 2039576 C1, IPC A61M 11/00, 1995.-   [6] Patent RU No. 2152829. “Device for ultrasonic dispersion of    liquid media”. V. N. Brezhnev, N. V. Kazarinova, A. V.    Pryanichnikov, A. V. Timonov.-   [7] Proceedings of Interregional Scientific and Practical    Conference, Omsk, 1998. Bulletin of SORAMN No. 2, 1999.-   Use of a new medicinal form—resonance ultradispersed aerosols of    essential oils of medicinal plants in treating chronic diseases of    respiratory organs (in Russian).-   L. D. Sidorova, G. L. Brezhneva, A. S. Logvinenko, E. Yu.    Korolenko, V. N. Brezhnev, A. V. Pryanichnikov.-   [8] “Meditsinskie Tekhnologii”, No. 1-2, 1995. Meditsinskoe    Informatsionnoe Agentstvo, St. Petersburg.-   Use of essential oils for preventing intra-hospital infections and    treating candidoses {in Russian).-   Kazarinova N. V., Muzychenko L. M., Tkachenko K. G., Shurguya A. M.,    Brezhnev V. N., Usov O. M.-   [9] OPINION on using an instrument for individual inhalations.    “Berdsk—Ultr Aeroil”. GOKG of Novosibirsk, 1999 (in Russian).-   [10] Patent RU No. 2045058, Byulleten' Izobretenij No. 27, 1995, Cl.    B01J, Gr. 9/10.-   [11] Applied Surface Science, vol. 108, 1, Dec. 23, 1996, pp.    95-103. Original instrumentation for new method of surface    investigation. V. N. Brezhnev and V. S. Tupikov.

1. A method for producing an aerosol, consisting in subjecting themedium to be dispersed to the action of ultrasonic oscillations with thehelp of a source of oscillations, which is made with a possibility ofdispersing a liquid and/or loose medium and adjusting the size ofaerosol drops by varying the oscillations, the liquid and/or loosemedium to be dispersed being acted upon in a standing-wave mode, and thefrequency of oscillations being varied within a range close to theresonance frequency of the macrostructure of the liquid and/or loosemedium to be dispersed, and/or being maintained equal to the resonancefrequency of the macrostructure of the liquid and/or loose medium to bedispersed to form a fine-dispersed aerosol with a size of drops notlarger than 0.5 μm, followed by regeneration of the dispersed mediummacrostructure.